Animals Have Stopped Turning White for Winter in Alarming Climate Change Trend

A snowshoe hare growing out its winter coat. Eric Bégin / Flickr

Wearing a white coat in the winter will help you blend into the background only if there's enough snow in said background. But with climate change making snowy winters shorter and rarer, white animals have to re-adapt.

Snowshoe hares, like ermines and arctic foxes, famously have two coats. To blend in with the ground in the warmer months, snowshoe hares sport brown fur. In the winter, they turn white to camouflage with the snow. It's harder for predators to spot an animal that matches the background in all seasons.

This technique is a wonder of evolution, but climate change is interrupting this process. With warming temperatures, there's less snow in the winter, and white hares on unusually snow-less ground stick out to predators, like tasty marshmallows on mud.

Research recently published in the Canadian Journal of Zoology explained the new phenomenon. Biologists studying in Pennsylvania and in the colder Yukon compared the habits of their respective snowshoe hare populations, and found the distinct populations act and look very differently. Pennsylvania hares have thinner coats and don't seek out warmer areas. Three of the 70 Pennsylvania hares captured didn't even grow out their winter coats, staying the same color all year long.

The winter coat is not only lighter in color, but also thicker than the summer coat. The researchers suspect that some Pennsylvania hares are bucking the winter-coat trend because they don't need the insulation in increasingly warm winters. Another possibility is that the hares that don't change have an advantage over those that do because they blend in more readily with the ground. The advantage could lead to non-changing Pennsylvania hares living longer, breeding more, and passing their genes of uninterrupted brown-ness to more baby hares.

Hares breed like rabbits so they can pass on their genes quickly. But climate change is fast, too. Will snowshoe hares adapt quickly enough as subsequent winters get warmer and produce less snowfall? The animals may have to migrate north to colder regions instead, ultimately affecting the ecosystem and the variety of predators that depend on hares for food.

This study focused on snowshoe hares, and we would need more research to better predict what will happen to these animals in coming years. Whether other animals that change colors in the winter will experience the same effect is still up to be researched.